Thromboembolism continues to be a major source of morbidity and mortality among multiply injured patients. Several areas of investigation remain inconclusive. Standard prophylaxis practice varies from center to center and lacks the support of level I recommendations. A group of investigators previously submitted requests for funding to study these questions but were unsuccessful. In evaluating our prior submission, the NIH reviewers were concerned about our assumptions of the prevalence of thromboembolism, the validity of the risk screening tool and the methods of testing for deep vein thrombosis (DVT). We wish to confirm and further validate these assumptions to support our future requests for funding.